The long range goal of this research program is to study the regulation of gene expression of DNA tumor virus genomes and to use this knowledge to understand the mechanism of eukaryotic gene expression and virus-host cell interactions. During the tenure of the proposed grant the following three aspects of human adenovirus type 5 gene expression will be studied. (l) Structure-function relationship of two virus-associated (VA) RNA genes will be studied to seek the molecular basis of their translation enhancement of viral mRNAs. Genetic approaches will be used to examine whether or not there is a functional correlation between the short complementary nucleotide sequences present in the VAI RNAs and the tripartite leader segments of adenoviral late mRNAs. In vivo nucleic acid cross linking approaches will be used to see if the VA RNAs interact with late viral mRNAs during translation. An adenovirus mutant will be constructed in which both VAI and VAII RNA genes are deleted. The phenotypic analysis of this mutant should reveal if the VA RNAs have functions in addition to their translation enhancement role. (2) The biological function of adenoviral early gene (Ll-early gene) located between 30.0 and 39.0 map units will be examined by constructing mutant viruses with mutations in the coding region of this gene. (3) The function of a protein coding sequence present in the i leader of the major late transcriptional unit will be examined by constructing an adenovirus point mutant. This point mutant will prevent translation of the i leader.